Rotary stepping switch



J1me 1965 R. M. ROVNYAK ETAL 3, ,3

ROTARY STEPPING SWITCH Filed Dec. 13, 1963 FIG.4

INVENTORS.

RICH ARD M. ROVNYAK TTY.

BY ARTEMUS w. PULFORD,JR.

United States Patent "ice 3,192,342 ROTARY STEPPING SWITCH Richard M.'R0vnyak, Hanover Park, and Artemus IW.

Pulford, Jr., Beiiwood, IlL, assignors to Automatic Electric Laboratories, Inc., Northlake, 111., a corporation of Delaware Filed Dec. 13, 1963, Ser. No. 330,311

- 3 Claims. (Cl. 200-105) This invention relates to electromagnetic devices, and more particularly to rotary stepping switches featuring at least one wiper arm assembly which rotates in a step by step manner through at least one row of normally closed contacts.

With the above type rotary switches it is necessary for the wiper assembly to include a knife-like actuator or wedge of dielectric material to open the normally closed contacts, and thereby open the electrical circuits connected to them. Such an actuator is disclosed in US. Patent 3,106,626, John M. Lord et al., issued April 5, 1963, and filed October 11, 1961. Although the actuator disclosed in this patent, as well as other actuators disclosed in the prior art, satisfactorily move and pass 'between normally closed contacts and interrupt electrical circuits, they tend to decrease contact reliability and thus the overall life of the switch as a result of not incorporating means to clean the contact surfaces from foreign elements. Without such means provided an accumulation may occur which will prevent the contacts from closing. The foreign elements may be dirt from the atmosphere or worn oflf dielectric particles. The latter occurs due to the nature of the dielectric material. Thus, the use of the dielectric actuator alone is not completely satisfactory and a means to clean the contacts from all foreign elements preferably each time the actuator passes through is called for. I Therefore, the principal object of the invention is to increase the reliability of rotary stepping switches having at least one wiper assembly adapted to engage a row of normally closed contacts.

Another object of the invention is to provide sucha wiper assembly without substantially adding to the cost of. manufacture of the switch.

To realize these objectives the invention features a switch with a Wiper assembly adapted to engage normally closed contacts. The wiper assembly includes a wiper having a hub portion, at least two pairs of radially projecting arms, and an actuator made of dielectric material. The arms extend toward a bank of contacts arranged in an arcuate pattern concentric with the axis of rotation of the wiper. One arm of each pair carriers a knife-like actuator which is designed and constructed to efiiciently move between the closed contacts in response to the rotational movement of the shaft, and thereby open the particular electrical circuit connected to them. The other arm of the pair extends substantially parallel to the actuator and includes a portion which is adjacent or follows the actuator through the contacts on the following rotational step, thus the term follower for it. The follower therefore cleans the contact surfaces after the actuator has passed through relieving them from dirt or other foreign elements which would tend to prevent closure of the contacts after the actuator has passed through. The follower is made as an integral piece with the hub and other arm and thus the cost of manufacture of a switch incorporating the feature is minimized. Moreover, it is made of conductive material so that the aforementioned electrical circuit closes at the moment the follower engages the contacts or as soon as the actuator leaves the same. The hub is fixed to the shaft and is insulated and separated from adjacent wiper hubs.

These and other objects and features will become more 3,192,342 Patented June 29, 1965 apparent upon making a perusal of the following detailed description taken with the accompanying drawings of which:

FIG. 1 is a top view of the wiper assembly according to the invention;

FIG. 2 is an end view of the wiper assembly shown in FIG. 1;

FIG. 3 is a top view of a rotary stepping switch in- .including a wiper assembly as shown in FIG. 1;

FIG. 4 is a side view of the rotary switch shown in FIG. 3; and

FIG. 5 is a perspective view of a normally closed contact which is subject to engagement by the wiper assembly shown in FIGS. 1 and 2.

Referring now to the drawings, FIGURES 3 and 4 illustrate an embodiment of a rotary stepping switch according to the invention. Sub assemblies of the switch are a frame structure assembly 100, a bank assembly 110, a motor magnet assembly 120, and two wiper assemblies 130 and 140.

The frame structure assembly serves as the support means for the other sub assemblies and consists of a frame 101, a rotatable shaft 102, and a ratchet wheel 103. One end of shaft 102 is mounted to the frame and the other end is mounted to the ratchet wheel. The motor magnet, on the other hand, is connected to an electrical energy source (not shown) and serves as the driving force for the switch. The wiper assemblies and more specifically the ratchet wheel is the recipient of this force and rotates in a step by step manner. The rotation of the ratchet wheel in turn rotates the wiper assemblies which engage the terminal contacts in the bank assembly. This engagement of the wiper assemblies with the terminal contacts thus brings about either the opening of the electrical circuits connected to the terminal contacts or the closing thereof, depending upon whether the contacts are the normally closed or the opened type.

More specifically, the aforementioned motor magnet assembly 120 consists of a coil 121, a core 122 with a pole face 123, a heel piece 124, an armature 125, a pawl 1:26, a detent 127, and a tension spring 128. The coil as aforementioned is connected to an electrical source and is wound on the core. The core in turn is mounted to the heel piece as in the armature 125. Pivotally mounted to an end of the armature is the pawl 126. Upon energizing the coil an electromagnetic field is set up and the armature is attracted toward pole face 123 thereby moving pawl 126 laterally so that it rides over one or more of teeth 104, of ratchet wheel 103, and compresses spring 128. Upon removing the energizing source spring 128 will restore the armature and urge the pawl against the teeth and rotate the shaft 102 a distance of one step, as calculated by the distance that the terminal contacts of a given row are apart-from each other. Therefore in effect the energizing of the coil cocks or presets the armature so that it can do work. The detent prevents the ratchet wheel from rotating in a reverse direction; it insures that the work done is in the proper direction.

The bank assembly supports the terminal contacts 111 which are arranged in rows and columns between arcuate-shaped insulators 112. The insulators are stacked between top plate 113 and a portion of frame 101 and can be molded of a plastic material, such as bakelite, or they can be made of a phenolic material. T 0 provide a row of normally closed contacts two rows are required with the contacts of each row formed so they touch the contacts of the adjacent row.

The wiper assemblies are of two types; the type 130, engageable with the normally open contacts and the type 140, engageable with the normally closed contacts and described in detail further on. Each assembly is rotatably mounted on shaft 102 and separated by spacers 136.

aieaeae Assembly 130 consists of a pair of wipers 131 and 135 each made of conductive material such as a phosphor bronze for example and having a hub 132 mounted on shaft 102 with two radially extending arms 133 and 134. The assembly is arranged so that wiper 131 is positioned on one side of a given row of terminals and wiper 135 is positioned on the opposite side thereof. The two wipers are separated by a spacer 136, however the extreme ends thereof are tapered toward each other to make good contact with the top and bottom surface of the terminals.

The invention concerns itself principally with the construction of the wiper assembly 140 which engages nor mally closed contacts such as illustrated by way of example in FIG. 5. Although only one such wiper assembly is disclosed it is to be understood that more than one could be included in the switch. In fact any combination of normally closed and normally opened contacts can be provided. Wiper assembly 140 is shown in FIGS. 1 and 2 and consists of a single wiper 148 also made of a conductive material and having a hub 141, two pairs of arms 142 and 143, and an actuator 144. The arms and hub are shown as one piece in the preferred embodiments to keep the cost of the switch at a minimum. It is to be understood however, that the arms could also be made as separate members and connected to the hub. The free end of arm 143 receives actuator 144 at its recess 150. The actuator, as aforementioned, is constructed out of dielectric material and also has a leading edge 151 and a trailing edge 152 to enable it to enter the closed contact without shock to the switch.

Main portion 153 of arm 142 is spaced from and parallel to the arm 143, however, the extreme end or follower portion 153 is preferably adjacent the trailing edge 152 of the actuator. This particular construction provides for a degree of flexibility needed to offset any irregularity in the plane of the terminal contacts. Moreover, with the follower 153 adjacent the actuator it goes through a given pair of closed contacts one step behind the actuator. It relieves the bounce that is ordinarily incurred after the trailing edge leaves the contacts as a result of being adjacent. The distance that the contacts must move in order to close electrically is thus diminished by the thickness of the follower. The contacts are closed electrically when the follower is between them even though they are not physically. By passing through the contacts the follower cleans the contact surfaces and removes any foreign elements accumulated thereon before intermittent contact failure occurs. The effect of this cleaning action therefore prolongs the life of the switch and increases its reliability, and thus achieving the objective set forth for the invention.

The invention has been described in detail in connection with a single embodiment, however, it should be realized that this was done by way of example only and not as a limitation upon the spirit and scope of the invention as defined specifically by the appended claims.

What is claimed is:

1. In a rotary stepping switch for controlling electrical circuits and including a row of normally closed contacts positioned in an are about a shaft which rotates in a step by step manner in response to the energization of an electromagnet, a wiper arm assembly comprising: a substantially fiat circular shaped hub rotatably mounted on said shaft and aligned with said row; at least one pair of projecting arms connected to said hub; and a dielectric actuator having a recessed port-ion, a knife-like leading edge, and a trailing edge to engage and pass between and open said contacts, said actuator being mounted on one arm of said pair at said recessed portion thereof, and the other arm of said pair including a main portion and a follower portion, said main portion being parallel to said first mentioned arm said follower portion being offset with respect to said main portion and positioned substantially adjacent said trailing edge to pass between and clean said contacts one stepafter said actuator passes between'said contacts.

2. In a rotary stepping switch for controlling electrical circuits and including a row of normally closed contacts positioned in an arc about a shaft which rotates in a step by step manner in response to the energization of an electromagnet, a wiper assembly comprising: a substantially fiat circular shaped hub rotatably mounted on said shaft and aligned with said row; a first and second pair of projecting arms connected to opposite sides of said hub; and a pair of dielectric actuators having a recessed portion, a knife-like leading edge, and a trailing edge, said actuators being mounted on one arm of each of said pair at said recessed portion thereof and said knife-like leading edge being at an angle with respect to said trailing edge to facilitate in the passing of said actuator betweensaid contacts, and said other arms of each pair each including a main portion and a follower portion, said main portion being parallel to said arm, said follower portion being made of conductive material and offset with respect to said main portion, said follower portion also being positioned substantially adjacent said trailing edge to pass between. and clean said contacts one step after said actuator passes between said contacts.

3. In combination, a frame, a shaft rotatably mounted on said frame, a stepping mechanism mounted on said frame to rotate said shaft in a step by step manner, a contact bank assembly including at least one row of normally open contacts and one row of normally closed contacts arranged between arcuate-shaped insulators and concentrically about said shaft, said contacts being angularly spaced apart to correspond to the steps of said shaft, 21 first wiper assembly including a pair of wipers having a hub portion and arms extending therefrom rotatably mounted on said shaft for bridging said normally open contacts, and a second wiper assembly including a substantially flat hub rotatably mounted on said shaft, a first means connected to said hub for passing between and opening said normally closed contacts, and a second means also connected to said hub and constructed and arranged to pass between said contacts one step behind said first means to clean said contacts.

References Cited by the Examiner UNITED STATES PATENTS 4/56 Persons 200-466 10/63 Lord et al. 200105 

3. IN COMBINATION, A FRAME, A SHAFT ROTATABLY MOUNTED ON SAID FRAME, A STEPPING MECHANISM MOUNTED ON SAID FRAME TO ROTATE SAID SHAFT IN A STEP BY STEP MANNER, A CONTACK BANK ASSEMBLY INCLUDING AT LEAST ONE ROW OF NORMALLY OPEN CONTACTS AND ONE ROW OF NORMALLY CLOSED CONTACTS ARRANGED BETWEEN ARCUATE-SHAPED INSULATORS AND CONCENTRICALLY ABOUT SAID SHAFT, SAID CONTACTS BEING ANGULARLY SPACED APART TO CORRESPOND A PAIR OF WIPERS HAVING A FIRST WIPER ASSEMBLY INCLUDING A PAIR OF WIPERS HAVING A HUB PORTION AND ARMS FOR BRIDGING SAID NORMALLY OPEN MOUNTED ON SAID SHAFT FOR BRIDGING SAID NORMALLY OPEN CONTACTS, AND A SECOND WIPER ASSEMBLY INCLUDING A SUBSTANTIALLY FLAT HUB ROTATABLY MOUNTED ON SAID SHAFT, A FIRST MEANS CONNECTED TO SAID HUB FOR PASSING BETWEEN AND OPENING SAID NORMALLY CLOSED CONTACTS, AND A SECOND MEANS ALSO CONNECTED TO SAID HUB CONSTRUCTED AND ARRANGED TO PASS BETWEEN SAID CONTACTS ONE STEP BEHIND SAID FIRST MEANS TO CLEAN SAID CONTACTS. 